Teoh was the third child of Teoh Leong Hwee (born 1953). He had an elder brother; Teoh Beng Kee (Chinese: 赵铭基) (born 1976), elder sister; Teoh Lee Jun (Chinese: 赵丽君) and a younger sister; Teoh Lee Lan (1980，Chinese: 赵丽兰). His father was a taxi driver, and his mother, Teng Shuw Hor (1953) is a housewife.
Teoh was engaged to 28-year-old teacher Soh Cher Wei after a two-year courtship, and had been planning to register his marriage with her the day following his death. A photo shoot on the same day, followed by a honeymoon and wedding reception in October had also been planned. At the time of Teoh's death, Soh was two months pregnant; she told the press she intended to keep the child. National Registration Department regulations only allow a father's name to be included on the birth certificate if he is physically present at the time of birth; after this was publicised through the press, Women, Family and Community Development Minister Shahrizat Abdul Jalil said she would ask the NRD to look into the matter. Shahrizat also stated her ministry would assist in transferring Soh from her current school to one closer to her hometown, and look into assisting Teoh's family since he was their sole breadwinner.
Prime Minister Najib Tun Razak later met with Teoh's family to express his condolences. Najib told them he would direct the Attorney-General and relevant government departments to look into Teoh's family's wish that his child bear the Teoh surname. On 15 August 2009, Soh completed the traditional Chinese marriage ceremonies, together with Teoh Lee Lan, Beng Hock's younger sister, acting as a proxy. Kerk Kim Hock, a distant uncle of Teoh and the family's acting spokesperson, told the press that completion of the marriage rites now entitled Soh to have her name engraved on Teoh's gravestone as his wife.
MACC officials claimed that the interrogation had lasted for about 9 hours. According to the MACC also, Teoh was freed at 3.45am—however without proper explanation, his possessions, including his mobile phone, remained in MACC custody. MACC officials also claimed that Teoh asked to stay the night at the MACC office, and was claimed to be last seen alive around 6am. Teoh was found dead at 1.30pm later in the day. The investigation had been into allegations that Ean Yong had paid RM2,400 for flags to be used in Merdeka Day celebrations, but not taken delivery of the flags. Teoh's colleagues who had also been questioned claimed that they were put under pressure from MACC officers, including being denied access to legal counsel and food or drink. Teoh's mobile phone was still in the possession of MACC officials when he was found dead at 1.30pm despite the MACC's claims that Teoh was released at 3.45am. The mobile phone was later handed to the police for investigation.
One of Teoh's colleagues, Tan Boon Wah, later filed suit against the MACC for false imprisonment. In the case, Tan Boon Wah v. Datuk Seri Ahmad Said Hamdan, Ketua Suruhanjaya, Suruhanjaya Pencegahan Rasuah Malaysia and Others, the High Court ruled that because Tan was interrogated after normal working hours, he had been subject to false imprisonment, and ordered the MACC to pay him damages. Tan's lawyer, Karpal Singh, said that Teoh's family could also sue the MACC for damages, citing this ruling. Democratic Action Party Parliamentary leader and former Opposition Leader Lim Kit Siang lamented that "Teoh Beng Hock would not have died if MACC had followed the law" and interrogated him during the day.
Teoh's family and others have called the MACC's version of events into question. When the investigating officer involved briefed the MACC's advisory board, several members of the board "asked why he chose to stay back. Any detainee would have run for his life! The investigating officer replied that since Teoh wanted to stay back, he allowed it." During this briefing it also emerged that no official records of Teoh's detention or his release existed. In August, a video of men in uniform assaulting a man in their custody began circulating as a supposed video of Teoh's interrogation. The Bukit Aman federal police headquarters denied the men were police personnel. The video had previously been circulated in June as a supposed example of police interrogation techniques, ruling out the possibility of it involving Teoh. A political observer attributed the video's popularity to the government's failing to provide adequate clarification about the circumstances of Teoh's interrogation: "The authorities are shedding little light about what happened to Teoh. This allows rumour mongers to spread ridiculous things."
Some lawyers have argued that the law does not authorise the MACC to hold witnesses in custody, and that since Teoh was not a suspect, he should not have been held in custody. The Malaysian Human Rights Commission called the duration of Teoh's questioning "inhumane and cruel." The president of the Bar Council, K. Ragunath, said the MACC had contravened the Federal Constitution by denying Teoh legal counsel during questioning, as well as the Lockup Rules 1953, which require all detainees to be locked up between 6.30pm and 6.30am to rest. Ragunath called Teoh's interrogation tantamount to torture. Ean Yong's lawyer insisted that as "Teoh's movement was restricted, this amounts to an arrest," despite the MACC's insistence that Teoh was only a voluntary witness. Mohamad Ramli Manan, a senior official who retired from the Anti-Corruption Agency (before it became the MACC), agreed:
Another former ACA official, Abdul Razak Idris, disputed Ramli's view of the interrogation process, saying: "The Act provides that we can interview anytime. Investigators are supposed to work 24 hours."
In response to calls from civil society and political leaders for a Royal Commission, Deputy Prime Minister Muhyiddin Yassin stated the Cabinet would consider setting up a Royal Commission of inquiry. Initial police findings suggested foul play was not involved in Teoh's death, but his friends and relatives insisted Teoh had not committed suicide, pointing to the fact that he was to be married, and that his fiance was pregnant. Teoh's family lawyers claimed that during questioning by the police, his family had been asked questions suggesting that they were primarily interested in "[absolving] MACC officers from liability" by pursuing the possibility of a suicide. A week after Teoh's death, his family vigorously insisted there was no possibility he had killed himself: "Teoh was joyful and had no problems at work. Teoh had no financial issues, got along well with everyone and was preparing for his wedding." One detail which seemed to strike the police was Teoh's shoes; when his body was discovered, his shoes were apparently significantly damaged and worn. Teoh's fiancee "said that Teoh had several pairs and seldom changed them unless they were damaged, but on that fateful day, he wore a new pair."
The United Malays National Organisation (UMNO)-owned newspaper Berita Harian published an op-ed by New Straits Times Press managing editor Zainul Ariffin Isa criticising the response to Teoh's death, stating that criticisms of the MACC were an attempt to undermine Malay institutions. Zainul was particularly critical of Selangor Menteri Besar Khalid Ibrahim for his criticism of the MACC officers' handling of the case, saying it was not right for Khalid to question "those of the same race as him."
At the weekly Malaysian Cabinet meeting on 22 July following Teoh's death, the Cabinet transferred all MACC officers involved in the probe of graft allegations against the Selangor government to other assignments, pending the official police inquiry. The Cabinet also decided to establish a Royal Commission of inquiry into the MACC's interrogation procedures, but not Teoh's death, allowing the standard inquest to pursue the matter.
In a joint statement, Pakatan Rakyat leaders called the Royal Commission's terms of reference insufficient, saying that the "question [of how Teoh died] cannot be separated from the more general issue of how the MACC conducts investigations." The Pakatan Rakyat statement insisted that the Commission probe the following questions:
Robert Phang, a member of the MACC advisory board, suggested that "Though the royal commission's scope is wide, it can be opened up further to dig deeper into issues not cleared by the inquest," such as establishing a reason for Teoh's death. Also being investigated is a mystery letter written on the letterhead of MACC, alleging MACC, Hishamuddin bin Hashim was involved with the torture of Teoh Beng Hock and former Menteri Besar Khir Toyo had prior knowledge of it.
The Royal Commission of Inquiry concluded that Teoh was not murdered but had committed suicide due to the aggressive interrogation tactics by three MACC officers. Teoh's family have rejected the RCI's findings and insisted that Teoh was murdered. The Bar Council of Malaysia have also questioned the RCI's findings. A coalition of 126 NGOs have called the Commission's findings a whitewash as it did not address the concerns regarding the interrogation methods by the MACC. Prime Minister Najib Tun Razak has defended the RCI's findings and called on all quarters not to question the findings. The Malay daily Utusan Malaysia, which is owned by UMNO, defended the MACC and blamed DAP for Teoh's death.
The three MACC officers involved in interrogating Teoh have been suspended pending an investigation by the police.
On February 10, 2012, Teoh Meng Kee, Beng Hock’s elder brother filed an application at the Court of Appeal to review the open verdict stating that Teoh Beng Hock committed suicide delivered by the Coroner’s Court in 2011, after his application was rejected by the High Court on December 1, 2011. The Court of Appeal on September 5, 2014 set aside the open verdict stating that "a person or persons were responsible" for Teoh's death.